Recently it was brought to my attention that on
some 1500cc Spitfires and Midgets there is a
clearance problem between the bottom of the intake
manifold and the exhaust manifold. If your car has
this problem it will have a massive vacuum leak and
exhibit the symptom of immediately dying upon
startup. Some solutions are creating clearance
between the manifolds by grinding or replacing the
exhaust manifold with an aftermarket header.